1. Field of the Invention
The present invention relates generally to a disc mounting system and method for attaching disc blades to an agricultural implement, such as a disc-ripper, and, more particularly, to such a mounting system and method in which each disc in at least the front disc gangs on the implement is mounted to a gang bar via a respective individual leaf spring. This allows each disc to individually move vertically, laterally and torsionally to relieve stress on the disc blade when an obstacle is encountered.
2. Description of the Related Art
Modern frames are faced with a variety of problems, including increased concern for soil erosion, crop residue management and rising production costs with stagnant crop prices. One way farmers are successfully addressing each of these concerns is to reduce, as far as possible, the number of passes which a farmer must make over his fields. In corn growing operations, after the corn is harvested, it is important for the farmer to conduct fall tillage to bury the crop residue from the harvested crop and to break up sub-soil compaction in preparation for spring planting. In order to accomplish both of these tasks in a single pass, disc-ripper implements have been developed. Typically a disc ripper has a pair of disc gangs mounted on the front of the implement with the gangs angled inward and rearward toward each other. The front disc gangs are mounted ahead of a number of ripper shanks distributed across the implement. Following the ripper shanks are another pair of disc gangs which are angled inward and forward toward each other.
These disc-rippers, which must be pulled by a large, high horsepower tractor, utilize the front disc gangs to bury the majority of the crop residue. The trailing ripper shanks serve to break up the sub-soil compaction and the trailing rear disc gangs are then used primarily to level any ridges created by the ripper shanks. One of the advantages of a disc-ripper implement is the tendency of the ripper shanks to drive deep into the soil, which makes the entire implement stay in the ground and work the soil consistently. At the same time, the discs are pulled down into the soil by the action of the ripper shanks, which causes them to be consistently buried and working as well. This means that the implement will also tend to stay in the soil and not ride up and over obstacles, such as rocks or extreme hard spots. This means that some relief must be afforded to the disc gangs, particularly on the front of the implement, to prevent the disc mounts from being damaged or the disc blades from being bent or broken as they encounter these obstacles.
In order to address these needs, prior art disc-rippers have attached the discs in a number of different ways. Often the discs are ganged together spindle to spindle and the entire interconnected gang is attached to a gang bar via spring mounts, such as U or C shaped leaf springs or compression coil springs. A problem with this arrangement is the requirement for the entire disc gang to ride up and out of the ground when any of the discs encounters an obstacle, which can result in broken individual discs in the gang and/or large undisced gaps in the field as the entire gang rides up and out of the soil and then settles back down into the soil.
In order to counteract these problems, it is known to provide individual spindle arms for each disc, with each arm having its own compression spring. This arrangement allows each disc in a gang to individually flex backward and upward through an arc dictated by the length of the arm. While this arrangement is an improvement on ganged discs, the discs are required to travel through a relatively long arc in order to clear an obstruction. In addition, if the obstacle encountered is slightly off center of the disc travel, a large amount of side load can be imparted to the disc, often resulting in bending or twisting of the arm, damage to the disc spindle or bearings or even breakage of the disc blade.
At least one prior art attempt has been made to attach individual discs to an implement via respective leaf springs. U.S. Pat. No. 2,750,861 to Robert Erwin, and entitled Mounting for Disc Type Soil Working Tools, is directed to such an arrangement. In the Erwin patent, a substantially U shaped leaf spring is attached, at an upper leg, to a seed hopper and, at a lower leg, to a disc mounting bracket. However, the leaf spring in Erwin extends across the top of the respective disc and extends at a considerable angle with respect to the path of travel of that disc. This arrangement allows the disc to be vertically deflected, but, intentionally, acts to restrain any lateral or twisting motion of the spring and disc. Thus, the Erwin leaf spring mounting system suffers from the same shortcomings as the coil spring mount described above.
It is clear then, that a need still exists for a disc mounting mechanism for ganged disc implements and disc-rippers which allows each individual disc freedom to move away from obstacles and hard spots. Such a disc mounting mechanism should preferably allow each disc to individually move vertically, laterally and torsionally to avoid obstacles without damage to the disc and mounting mechanism. The disc mounting mechanism should also allow debris and trash to freely flow through the discs without impeding the operation of the implement.